The indicator dye, phenol red, is useful for measuring pH values between 6.8 and 8.4. You will use phenol red to observe changes in pH that result from the acidity of the fatty acids that are formed as the triglycerides in cream are digested forming fatty acids and glycerol. You will add NaOH (sodium hydroxide) to all tubes at the start making all tubes initially alkaline. The more enzyme activity, the more fatty acids, the more acid (lower pH), the more "yellow" the tube will become.
+++
Fuschia
Alkaline
None
. . . . . . .
++++
Red
Neutral
Some
++
Yellow
Acid
Most
Color
Symbol
Description
pH
Amount of Lipase Activity
pH
Color
(of Indicator)
acid
yellow
neutral
red
(this may be a peach color)
alkaline
pink
(this may be fuchsia or "hot" pink)
tubes in water bath for 20 minutes
Bile Salts
Fat digestion is facilitated by the presence of bile salts (a component of bile produced in the liver), which bring about a physical (not enzymatic) breakdown of large fat droplets into smaller particles. This process is called emulsification.
From http://samson.kean.edu/~breid/enzyme/enzyme.html
Phenol Red Indicator Dye
The indicator dye, phenol red, is useful for measuring pH values between 6.8 and 8.4. You will use phenol red to observe changes in pH that result from the acidity of the fatty acids that are formed as the triglycerides in cream are digested forming fatty acids and glycerol. You will add NaOH (sodium hydroxide) to all tubes at the start making all tubes initially alkaline. The more enzyme activity, the more fatty acids, the more acid (lower pH), the more "yellow" the tube will become.Bile Salts
Fat digestion is facilitated by the presence of bile salts (a component of bile produced in the liver), which bring about a physical (not enzymatic) breakdown of large fat droplets into smaller particles. This process is called emulsification.